1. Field of the Invention
This invention relates to a heavy duty detergent powder comprising predominantly soap and an improved process for producing the same. More particularly, this invention relates to a heavy duty detergent powder in the form of relatively coarse particles of soap having a low moisture content which can easily be disintegrated and an improved process for producing such a detergent powder in a single step which comprises neutralizing a fatty acid having, optionally, dissolved therein at least one nonionic surface active agent with a powdered hydrous sodium carbonate at a temperature higher than the melting point of the fatty acid used.
2. Description of the Prior Art
The laundry soap powders commercially available at present generally comprise 45 to 55 % by weight of soap, 25 to 35 % by weight of soda ash, 0 to 10% by weight of sodium sulfate and 15 to 25 % by weight of water, and are prepared by a process comprising thoroughly mixing a soap paste with soda ash in a mill, allowing the resulting soap to stand in a solidification frame to solidify the mixture, cutting the soap to produce soap bars, and crushing or disintegrating the soap bars with a crusher or a disintegrator to obtain a soap powder. The above-described conventional process involves a number of cumbersome steps and requires a prolonged processing time and much labor. Further, the product obtained from such a conventional process has various problems which remain unsolved, for example, the product generally exhibits poor flowability and tends to cake.
Soap is an excellent detergent because of its non-toxicity and high biodegradability and thus it can be safely used without the possibility of environmental pollution, but it possesses a serious disadvantage for household use in that the detergency of soap is drastically lowered at low temperatures and that a metal soap formed by reaction of the soap and the metal ions contained in water tends to be deposited on laundry, such as textiles, thereby hardening the texture of fibers. These disadvantages can be eliminated by incorporating 10 to 20% by weight of nonionic surface active agents, etc. into pure soap, but the solid mass of such mixtures generally tends to be softened and becomes tacky. Thus, disintegration of the solid mass into fine particles is difficult resulting in poor water-solubility and caking is easily caused.